It has been suggested that certain derivatively coupled nonrenormalizable scalar field theories might restore the perturbative unitarity of high-energy hard scatterings by classicalization, i.e., formation of multiparticle states of soft quanta [2]. Here we apply the semiclassical method of calculating the multiparticle production rates to the scalar Dirac-Born-Infeld theory, which is suggested to classicalize. We find that the semiclassical method is applicable for the energies in the final state above the cutoff scale of the theory, $L_{*}^{-1}$. We encounter that the cross section of the process $2\to N$ ceases to be exponentially suppressed for the particle number in the final state $N$ smaller than a critical particle number $N_{\mathrm{crit}}\sim (E{L}_{*}{)}^{4/3}$. It coincides with the typical particle number produced in two-particle collisions at high energies predicted by classicalization arguments.

• Received 6 July 2012

DOI:https://doi.org/10.1103/PhysRevD.86.105008